How do you know which standards to keep?

I have very high standards. I want a guy who’s as similar to me as possible. However i’ve made a mistake and rejected perfectly good guys over small things like their major or how lazy they seemed (not ambitious/passionate).
I find myself still single and find it very hard to even run into these guys now and i’m starting to think that perhaps I should lower my standards if I plan on finding anyone and that the main thing that matters is how they treat me.
I am currently talking to this guy and he’s great but he smokes weed and I don’t and never plan on doing it. I wanted a guy who doesn’t smoke weed but im not sure if that’s a reasonable standard to have or not if he’s perfect otherwise. What do you guys think? Am I nitpicking again?
How do you know which standards to keep?
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